Fatal error on line 500 after upgrade to 3.6

Hi there,

I’m trying to run the upgrade from 3.5.2 to 3.6 and during the process (accessed via ‘install now’ in the dashboard get the following error:

Fatal error: Call to undefined function wp_safe_remote_get() in /websites/123reg/LinuxPackage22/ra/ch/el/rachellucie.co.uk/public_html/blog/wp-admin/includes/file.php on line 500

I had deactivated the plug ins, and now can’t reactivate them, either, this gives error:

Fatal error: Call to undefined function wp_unslash() in /websites/123reg/LinuxPackage22/ra/ch/el/rachellucie.co.uk/public_html/blog/wp-admin/includes/class-wp-plugins-list-table.php on line 25

123-reg tell me that as this is an issue with the 3rd party package being hosted, this issue is nothing to do with them.

Please can you help!

url http://blog.rachellucie.co.uk

Rachel